Hurricane Bertha was expected to weaken as it makes its way between the East Coast and Bermuda on Tuesday (Aug. 5), the National Hurricane Center said in its Monday night update.

Bertha, which is forecast not to be a threat to land, is moving toward the north-northwest at about 20 mph, and is expected to take a turn toward the northeast with increasing forward speed. At 10 p.m., it was about 490 miles west of Bermuda.

The storm's maximum sustained winds are near 75 mph, just barely hurricane strength, with gradual weakening forecast over the next 48 hours. Hurricane-force winds extend outward up to 25 miles.

Daniel Brown, a senior hurricane specialist, wrote that Bertha may only have a short time left as a hurricane. "Bertha certainly does not look like a typical hurricane in satellite imagery this evening. ...

"Bertha is forecast to gradually weaken during the next day or two while it moves into an area of increasing southwesterly vertical wind shear and over decreasing sea surface temperatures. On Wednesday, the cyclone is expected to interact with an approaching mid-latitude trough and Bertha is forecast to become an extratropical cyclone over the North Atlantic shortly thereafter."

On Sunday, the storm buffeted parts of the Bahamas and the Turks & Caicos with rain and gusty winds, after passing over the Dominican Republic and causing temporary evacuation of dozens of families as its downpours raised rivers out of their banks. Earlier, it dumped rain on Puerto Rico, which has been parched by unusually dry weather.

Before Bertha reached the Turks & Caicos, residents pulled boats ashore or moored them at marinas in the tourism-dependent archipelago that has little natural protection from strong storm surges. Tourism Director Ralph Higgs said hotels were "taking the threat of the storm seriously."

The Associated Press contributed to this report.

View full sizeA weakening Hurricane Bertha was moving north at 20 mph Monday night, as seen in the center of this satellite image. NOAA GOES Floater satellite